This invention relates to apparatus for cutting vegetation and the like, and more particularly relates to improved apparatus for cutting vegetation with a flexible non-metallic cord member.
It is well known to cut or mow grass, weeds and other vegetation with a moving flail-like member, and it is now well known to employ a flexible non-metallic cord member for the purpose of cutting vegetation located in places which are inacessible to apparatus employing a rigid steel blade. In particular, the trimmer which is marketed in various forms under the trademark WEED EATER, and which is described in U.S. Pat. Nos. 3,708,967; 3,826,068; and 3,859,776; is now widely known and used for this purpose.
This invention relates to an improved cutting assembly in the form of a rotary head for a rotary edger, trimmer or the like. The preferred embodiment is in the form of a portable hand-held type edging tool wherein the cutting element is safe in most uses and avoids the hazardous conditions created by prior art devices. More particularly, the cutting assembly disclosed herein is of the type depicted in Ser. No. 746,685, and is an improvement thereover.
There is also depicted and described in U.S. Ser. No. 746,685, a cutting and trimming device having a head member arranged to be rotated, and containing a spool housed therein. A length of flexible non-metallic line is coiled about the spool whereby the free travelling end of the line extends generally peripherally from the head member and whereby the free travelling end will be swung arcuately about upon rotation of the head member to cut adjacent vegetation in the manner of a flail.
On the other hand, the device of Ser. No. 746,685, is also subject to certain minor disadvantages of a magnitude such as not to limit its practical value but which reduce the efficiency thereof to a slight degree. In the first place, it has been found that during extended usage of the device, substantial heat is generated within the motor housing particularly due to the presence therein of a full wave bridge rectifier. Because of the internal resistance of the rectifier, the generated heat has at times been sufficient to actually soften or melt the plastic of the motor housing adjacent the rectifier.
One attempt to solve the heat generation problem has been to provide air circulation openings in the tubular handle of the device. Such openings, however, have not provided sufficient cooling during extended usage since they are not in direct communication with the rectifier where a substantial portion of heat is generated.
The disadvantages of the prior art, are overcome with the present invention, and commercially acceptable embodiments of a vegetation cutter and the like are herein provided which are not only fully capable of cutting vegetation under most operating conditions, but which are also fully capable of other tasks completely beyond the capabilities of prior devices, such as cleaning dead leaves, trash and other such debris from along fences, walls and the trunks or stems of trees and bushes. More particularly, however, the embodiments of the present invention are capable of operation with a much higher efficiency and much lower breakage rate for their cutting strings.